The present disclosure relates in general to bearings and in particular to flexure based bearings.
Precise, parallel motion is optimal, for example, in optical devices such as polarization modulators. The amount of translation may be on the order of a fraction of a millimeter. In some applications, the optical device must operate in a cryogenic environment. Known parallel plate interferometric devices use three linear actuators equally spaced around the optical elements to establish plate spacing, tip and tilt. The three actuator systems have fairly complex control systems, and there is inevitable cross-coupling between the controlled axes. Cross-coupling leads to position noise and lower control bandwidth.
Single actuator, linear roller bearing systems are known, but do not have sufficient accuracy. In addition, when the greases are removed for cryogenic operation, the bearings have a short life. Traditional double blade flexure bearings have internal stresses, which cause them to deflect unacceptably upon cooling. Thus, there is a need for a single actuator bearing system that can operate accurately in cryogenic temperatures.